Oil circuit breaker



April 23, 1929.' F. STERN l OIL CIRCUIT BREAKER Filed Sept. 2. 1926Patented Apr. 23, 1929.

UNITED rSTATESY PATENToFFICE.

FERDINAND STERN, OF BADEN, SWITZERLAND, ASSIGNOR TO AKTIENGESELLSCHAFTBROWN BOVERI & CIE., OF BADEN, SWITZERLAND, A JOINT-STOCK COMPANY 0F OILCIRCUIT BREAKER.

Application led'september 2, 1926, Serial No. 133,117. and in GermanyOctober 5, 1925.

This invention relates to the construction of circuit breakers, of theoil quenched type, 'for high tension service. I

A general 'obfect ot the invention is the provision of improvedconstruction tor such devices which will afford increased insulatingstrength between the contacts or poles across which the circuit isopened. I

An ancillary object is the provision of a construction which willlikewise afford in-r creased insulating strength between the contactsand the walls ot' the tank and other metallic portions ot. theapparatus.

A further object is the provision of a construction which will eil'fectconservation of space and material in the construction oit such devices,without sacrilice of insulating ecctiveness.

Other and further objects olE the invention will be pointed out orindicated hereinafter or will be apparent to one skilled in the art uponanl understanding of the invention or its employment in practice.

In the accompanying drawing forming a part of this specification, Iillustrate in diagrammatic fashion one arrangementfor embodiment ot theinvention but it is to be understood that this is presented forillustration only and is not to be accorded any interpretation havingthe eifect of limiting the claims short of the true and mostcomprehensive scope of the invention in the art.

In the drawing,

Fig. 1 is a cross sectional View, diagram matie in nature, of a two poleoil circuit breaker, showing in a general way the tension ields aboutthe poles or conductors car-- rying current in opposite directions, thesection being taken on the line 1-1 in Fig. 2; and

Fig. 2 is a part sectional elevation, dian grammatic in nature, of sucha device containing the invention, the section being taken on the 'line2-2 in Fig. 1.

In oil immersed circuit breakers for the handling` of high tensioncurrent, it is customary to provide mechanically operated.

means for opening and closing the circuit under oil, across fixedterminals or contact members. Necessarily, a proper strength ofinsulation must be maintained between these poles in order to preventflashing over or the establishment of an arc when the circuit breaker iseither open or closed or in the process ot opening. Various arrangementshave been resorted to for strengthening the insulation afforded Aby theoil and the spacing ot the terminals. The present invention provides aneffective construction for this purpose. In the arrangement showndiagrammatically in the drawing, the reference numeral 10 designates thetank of the circuit breaker in which extend conductors 11 terniinatingin contacts 12, one ot', said conductors 1l being` the iii-leading lineand the other being the out-leading line. Movable contacts 14 arecarried by and conductively connected through a yoke 15, which iscarried on vertically movable links 16 so that the contacts 14 may bemoved downwardly away from contacts 12 to open the circuit. The tank l()is lilled with oil to a proper level submerging the contacts. Disposedin positions encompassing the contacts are cylinders 17 of insulatingmaterial, saine being slotted at their lower portions, where necessaryto accommodate the vertical movement of the yoke 15. The cylinders 17are disposed in eccentric relationship so that their positionscorrespond generally to the equipotential zones of the tension fieldsurrounding the contacts 12 and conductors l1. In Fig. l the dottedlines indicate generally the lines of force of the electrostatic field,and the dash line circles are to indicate generally areas ofequipotential. With the respective cylinders '17 thus locatedapproximately in equipotential areas, they are not subjected to eXtremedifferences in potential between different points on their surfaces, andthus do not present creepage surfaces conducive to discharges which mayresult in flash-overs, as by this arrangement the electrical strain willbe everywhere approximately at right angles to the insulating material.

A further important result accrues from this eccentric arrangement ofthe insulating cylinders, in that it makes for conservation of spacewithoutdecrease of insulating strength. For high tension and eXtra hightension circuitbreakers this is of great economical importance, as itavoids the necessity for extremely wide spacing of the terminals, andthereby avoids necessity for extremely large tanks and the requisitelarge quantity of oil necessary to till them.

W'hat I claim is:

l. In a circuit breaker, the combination with a tank and series switchcontacts therein, of insulating shields encompassing the contacts ineccentric relationship with respect thereto, and oil submerging thecontacts and shields.

2. In a circuit breaker, the combination with the circuit breaker tankand a plurality ot sets oli series-opening switch contacts therein, ofinsulating shields encompassing suoli sets of contacts and lyingrespectively in areas about such sets o substantially equipotential, andoil submerging the contacts and shields.

3. In a circuit breaker, the combination of a tank, oil therein,stationary contacts in the tank, connected movable contacts forconnecting the stationary contacts, and insulating shields encompassingthe contacts in eccentric relationship with respect thereto.

4l. In a circuit breaker, the combination ot a tank, oil therein,stationary contacts in the tank, movable contacts 'for closing on thestationary contacts, an operating member between the movable contacts,and insulating shields encompassing the contacts, the shields associatedwith respective stationary contacts being arranged in eccentricrelationship with respect thereto.

5. In a circuit breaker, in combination,- a tank, line terminalstherein, movable contacts Afor connecting said terminals in series,means connected between the movable contacts ttor operating them, andinsulating shields encompassing respective terminals in eccentricrelationship with respect thereto.

(i. In a circuit breaker, in combination, a tank, anv in-leadingterminal and an out-leading terminal therein, a switch device 'forconnecting said terminals, an operating member Ytor said switch device,insulating shields encompassing the terminals, the shields associatedwith respective terminals being arranged in eccentric relationship withrespect thereto, and oil immersiug the shields and switch device.

7. In circuit-ln'eaking apparatus, contact elements, and insulatingmembers disposed about said elements in eccentric relation with respectthereto and with respect to each other.

In testimony whereof I have hereunto suhscrihed my name at Zurich,Switzerland, on the 12E day of August, A. I). 1926.

FERDINAND STERN.

